1. Field of the Invention
The present invention relates to a polymeric membrane, a method of producing this polymeric membrane and its use as well.
2. Description of the Prior Art
In the prior art there exist two groups of polymeric membranes which can be applied as subroof membranes, also called underlay membrane or "pliable sarking and underlays" or "underslating".
The representatives of the first group are predominantly based on a basis of polyvinylchloride containing a plasticizing agent and display generally a thickness between 0.5 and 1.0 mm. They have the advantage of being able to be welded by means of hot air or heating wedge apparatuses.
However, they have among others the drawback that their permeability regarding water vapor is generally considerably lower than 40 g/m.sup.2 day (23.degree. C., 90% relative humidity). Therefore, high demands must be posed regarding the quality of workmanship when laying the membrane. Similarly, the application at roof constructions with a high inherent humidity is generally problematic.
The representatives of the second group contain no uniform material basis. Their main feature is that due to very fine pores with partly clearly above 100 g/m.sup.2 d (23.degree. C., 90% relative humidity) they display extremely high permeabilities regarding water vapor. The products of this group are generally thinner than 0.5 mm. The drawback of these polymeric membranes is that partly due to the low thickness of the material, partly due to the used duroplastic raw materials, they can not be welded together at conditions present at a building site.
Therefore, subroofs having no seams cannot be produced, with the consequence that these subroofs can fulfill the function of an emergency covering only un-completely.
Connections of such subroof membranes to polymeric waterproofing and roofing membranes on flat roofs at the transition from sloping roofs to flat roofs are intrinsic regarding the execution.